14 BULLETIN : MUSEUM OF COMPARATIVE ZOOLOGY. 



metamorphosis of the head consists largely in an elongation. By Hen 

 neguy's method the neck-body is only rarely stained. This explains its 

 absence in Figures 142-154. By Heidenhain's method it becomes in 

 all spermatids a very conspicuous black spherical body (Plate V. 

 Figs. 196-200). 



I pass now to a consideration of the results reached by other students 

 of spermatogenesis in insects. 



Sabatier ('90) has discussed in a short article the spermatogenesis of 

 the Locustidae. The conclusions to which he comes are rather startling. 

 In regard to the metamorphosis of the spermatid, he says : " Pies du 

 noyau mais non a son contact immediat apparait dans le protoplasme une 

 vesicule spherique ... la vesicule protoplasmique." Sabatier main- 

 tains that there is an almost total degeneration of the nucleus, but ad- 

 mits that it gives rise to the " Kopfkappe " : " Cette derniere derive 

 done du noyau et fournit un exemple remarquable de la degenerescence 

 ou alteration du noyau de la cellule spermatique." It is quite remark- 

 able that the nucleus is able to form only the Kopfkappe when, presto, 

 " cette vesicule devenue fusiforme et vivement colorable constitue ce que 

 l'on considere comme la tete du spermatozo'ide." 



I have never seen any such nuclear degeneration, nor any extra- 

 nuclear vesicle of such paramount importance. The head of the Calop- 

 tenus spermatozoon arises from the six chromosomes inherited by each 

 spermatid. 



Blochmann ('87) describes the formation of the polar bodies in Blatta 

 germanica. 



The work of vom Rath ('91 a and '92) on the spermatogenesis of 

 Gryllotalpa must receive special notice. My account of the spermato- 

 genesis of Caloptenus confirms a large part of vom Bath's results, but 

 differs from his in several points, and suggests another interpretation 

 of the last two divisions. What these differences are will soon be 

 apparent. 



Vom Rath ('93) has already called attention to the many groups 

 of animals in whose spermatogenesis or oogenesis ring formation and 

 Vierergruppen have been observed by different authors ; but with one 

 exception (Flemming, '87) he mentions those authors only who have 

 noticed and remarked about these chromatic figures. It may seem ven- 

 turesome, but I wish to suggest the same interpretation for the figures 

 of various authors who either had no definite idea of Vierergruppen, or 

 considered the conditions exhibiting them abnormal (Flemming, '87), 



